Field of the Invention
The invention relates to medical pattern recognition systems and methods. More specifically, the field of the invention is that of training software for detection of retained foreign objects.
Description of the Related Art
Techniques are known for the identification of implanted medical devices (“IMDs”) and retained foreign objects (“RFOs”) in medical images.
Approximately 25 million patients in the United States have or have had an implanted medical device (“IMD”). Driven by a rapidly increasing aged population and supported by new technologies, the demand for IMDs and their further proliferation can only be expected to increase.
An IMD is a medical device that is partly or totally surgically inserted into the human body or a natural orifice and is expected to remain implanted for an extended period or may be permanent. IMDs can further be classified as either active, those that use electricity, or passive, those that do not use electricity. In the US, medical devices are regulated by the FDA and classified into three classes, on basis of risk and the level of regulatory control that is necessary to assure the safety and effectiveness: class I, class II, and class III. Class III devices include devices that generally affect the functioning of vital organs and/or life support systems with very high health risk if the device were to malfunction.
Identification of an IMD during patient admission, and especially in emergencies, is crucial for the safe and efficient management of that patient. Concerns with the accurate and timely identification of IMDs are an emerging safety issue. Of particular concern is the commonly encountered situation where medical records are not available and/or the patient is unable to provide the appropriate information/documentation regarding the IMD he has. Most commonly IMDs are initially reported by patients or noted on admission and/or emergency xrays (“XRs”), magnetic resonance images (“MRI”), ultrasound or computerized tomography (“CT”) images, necessitating, often ineffective, attempts to gather more information regarding the device in question. This usually involves contacting the patient's family, primary care providers or health care institutions previously visited by the patient. Even when such attempts are successful, available information about the patient's device is often incomplete, unreliable and delayed. On the other hand, the large variety, rapidly increasing number approved by FDA, and difficult projections/orientations of IMDs in medical images (XR, CT, or MRI) make their identification very difficult for radiology specialists. Possible consequences include: delayed appropriate diagnostic imaging and care, medical complications arising from device incompatibility with imaging or therapeutic modalities, and suboptimal care due to inappropriate avoidance of treatment and diagnostic procedures that are erroneously considered contraindicated.
Software applications facilitate initial assessment/identification, expedite the management, and improve the healthcare and safety of patients with IMDs, including those with symptoms of IMD malfunction. They also facilitate implementation of recent FDA requirements for post-market device surveillance.
Physicians are increasingly encountering patients with IMDs. Identification of an IMD, during an emergent admission in particular, is critical for safe and efficient patient management. In 2007, FDA issued a report indicating an increase in adverse events linked to medical devices, including 2,830 deaths, 116,086 injuries, and 96,485 device malfunctions. Class III active IMDs were cited in a relatively high number of fatality reports within the FDA report.
Ultra-low-power radio-frequency (RF) technology has greatly facilitated the development of IMDs. The ability to wirelessly transmit the patient's and IMD's data enables a clinician to obtain useful diagnostic information and reprogram therapeutic settings. Furthermore, radio-frequency identification (RFID) technology uses radio waves to transfer data from an electronic tag to identify and track the tagged device. However, the rapidly increasing number of IMDs and their manufacturers, absence of the standardized tools/methods capable of RF sensing, identifying, and reprogramming IMDs, radio interference problems, ethical/security issues, and the fact that many IMDs do not have RF capabilities make this technology less convenient for rapid identification. This disadvantage is particularly obvious in medical emergencies and emergency room settings.
Medical errors involving IMDs, especially those arising from their incompatibility with treatment or diagnostic procedures, are an emerging patient safety issue. Procedures incompatible with patient's devices have been performed, leading to device malfunction and other complications. Examples of such complications include: patients undergoing Magnetic Resonance Imaging (MRI) in the presence of implanted ferromagnetic devices possibly causing migration, interference with the function of implanted devices because of strong magnetic fields (MR) and disrupting electrical forces (certain types of CT or surgical electrocautery). This includes setting changes of active (none turned off) cardiac pacemakers and defibrillators and/or defibrillation shocks during surgical procedures caused by electrocautery scalpels. In another example, percutaneous catheters and ports have been damaged by exceeding their pressure ratings during therapeutic infusions, necessitating subsequent surgical interventions/exchange or repair. Furthermore, several IMDs are compatible with MRI and CT imaging but/and/or requires reprogramming after the completion of the MRI which has been frequently missed. These effects on the IMD are not always evident or immediately observed (such as unintended re-programming, e.g., ventriculo-peritoneal shunts' valves) and can not only lead to delays but also to serious and possibly disastrous complications. Conversely, there are patients that do not receive optimal treatment and diagnostic procedures, even though their devices are compatible with such treatments. For example, several pacemakers currently on the market are compatible with MRI. In these cases, disclosure software identifies these specific models as being compatible with MRI, providing the treating physicians an option to have their patient undergo a medically-indicated MRI scan safely.
Retained foreign objects (RFOs) in patients due to oversights during surgery, objects including needles and surgical instruments and/or materials, continues to be a significant problem with an incidence of between 0.3 and 1.0 per 1,000 surgeries. This has resulted in a significant increase in patient care costs and consecutive legal expenses.
Intra-operative or early post-operative identification of RFOs is critical for safe and efficient management of surgical patients. Current recommendations for prevention of RFOs in the operating room (“OR”) include methodical wound exploration before closing, usage of standardized practices for surgical items accounting, usage of items with radioopaque markers within the operative site, and mandatory operative field X-rays before wound closure when a item count discrepancy occurs. In addition, radiographic screening is recommended at the end of an emergent surgical procedure, unexpected change in the procedure, and for patients with a high body mass index. Some institutions also conduct routine postoperative screening radiographs for the prevention of RFOs. Therefore portable X-ray radiological protocols have become crucial for timely RFO detection. However, they have relatively low efficacy and require significant time for completion and for evaluation. The underlying problems of their use are the relatively low sensitivity and specificity of the human eye in the identification of relatively small objects in a large X-ray field and the fact that radiologists and surgeons do not routinely undertake formal training in the recognition of RFOs.
Technological aids to assist the OR team in the detection and prevention of retained sponges, gauze towels, and laparotomy pads include radio-frequency detectable sponge systems and bar-coded sponge systems. These aids are intended to augment the standardized manual count practices, and to not replace them.
Operative field X-ray is mandatory when there is a counting discrepancy of surgical instruments or materials at the end of the procedure. According to the 2006 Patient Care Memorandum of the Department of Veterans Affairs (Boston Healthcare System, VA, USA), surgical instruments and/or materials must be counted, except for procedures that are routinely concluded with a radiograph (for example, an orthopedic case to assure proper alignment of a bone or implant). In these cases, a radiograph is mandatory if an instrument count is not performed, and the evaluation of the radiograph must be performed before the patient is transferred from the OR to determine whether any instruments have been retained. When a radiograph is requested to locate a missing item, the type of foreign object that is missing, OR number, and telephone number must be specified in the request to the radiologist. Radiographic screening is also recommended/mandatory at the end of emergent surgical procedures, unexpected changes in procedures, or in patients with high BMI (e.g. >=20). Some institutions use postoperative screening radiographs routinely. In all of these cases, the completion of the surgical case may be delayed until radiologic evaluation is received. Assuming the patient is stable, current recommendations are that in the event of an incorrect count, a X-ray of the operative field should be made available to a radiologist within 20 minutes and their evaluation/confirmation of the results of the x-ray should be provided back to the OR within another 20 minutes. This process frequently takes significantly more time than 40 minutes.
Portable X-ray is also a method of choice for determination of the relative position/location of a RFO. This is particularly important if the specific tissue layer or surgical incision/wound is already closed and additional instruments are present in the X-ray image.
While stainless steel instruments are likely to be detected successfully on radiograph screening, radiographs are less sensitive in detecting sponges and needles. Sponges may be difficult to detect because they may become twisted or folded, distorting visualization of the marker. Needles may also be difficult to visualize due to their size. The value of intraoperative and/or post-operative X-ray images for RFO identification has been controversial and very few studies have been undertaken to evaluate their effectiveness. A recent study evaluating portable X-rays for identification of retained suture needles in ophthalmologic surgical cases showed that the overall sensitivity and specificity of the physicians' review of radiographs with suspected retained needles was 54% and 77%, respectively. This is particularly worrisome considering that in this particular case the size of the surgical field was small, the area of interest well-defined, while the participants in the study have known that they were looking for the needles which should have greatly facilitated RFOs/needle detection. In the most studies when radiographs were falsely negative for RFO detection; poor-quality radiographs, multiple foreign objects in the field, and failure to communicate the purpose of the radiograph to the interpreting radiologist were cited as contributing factors. Although it is mandatory that such intra-operative radiographs be reviewed by a radiologist(s) and/or surgeon(s), it is not routine for those individual to have undertaken specific/formal training in the radiographic identification/recognition of these objects. Furthermore, the general consensus throughout the literature is that the most effective means of evaluating the presence of a RFO is through the use of CT scanning which—in most of the cases—is not possible in the OR.
Even when attuned to the problem of RFOs, both physicians and detection software suffer from the lack of samples with which to test. Physicians, and particularly radiologists, are infrequently provided a scan image having an RFO so that they have no opportunity to develop their skills in this area. Detection software, similarly, is difficult to test and develop because the lack of such images.